boron

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: It will be appreciated from the foregoing that impure boron, in the form of aqueous boric acid, can be converted to a borate ester, such as trimethyl borate. The ester is may then be removed from the solution, together with methanol and water, by distillation (followed by condensation and cooling) to yield a purified methanol-trimethyl borate solution. Typically, this distilled solution will contain about 75% by mass trimethyl borate. This highly concentrated solution is then mixed with water to obtain boric acid via the hydrolysis reaction of REACTION 3: B(OCH3)3+3H2O⇄B(OH)3+3CH3OH  (REACTION 3) Addition of water to the trimethyl borate solution converts the trimethyl borate to purified boric acid, which can then be recrystallized or precipitated from the solution. The methanol and water may then be distilled and recovered for reuse. The ester is may then be removed from the solution, together with methanol and water, by distillation (followed by condensation and cooling)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a suspension of N-(4-trifluoromethylbenzyl)-5-(2,4-dioxothiazolidin-5-yl)methyl-2-methoxybenzamide (800 mg) in anhydrous methylene chloride (30 ml), a 1.0N boron tribromidemethylene chloride solution (2.20 ml) was slowly added dropwise in an argon atmosphere under cooling with dry ice-acetone and stirring. After stirred for 6 hours at room temperature, the reaction liquor was allowed to stand for 3 days. After water was added and the mixture was stirred for 30 minutes, this was concentrated under reduced pressure. Ethyl acetate was added to the residue, which was washed with water and then dried over anhydrous sodium sulfate. This was concentrated under reduced pressure and the residue was purified by means of silica gel column chromatography (developing solvent; methylene chloride:methanol=40:1) to obtain 618 mg (80%) of aimed compound as crystals. These were recrystallized from ethanol-water to obtain purified aimed compound as a light brown powdery crystals. Melting point 146.0~148.0° C. After stirred for 6 hours at room temperature the mixture was stirred for 30 minutes this was concentrated under reduced pressure Ethyl acetate was added to the residue, which was washed with water dried over anhydrous sodium sulfate This was concentrated under reduced pressure the residue was purified by means of silica gel column chromatography (developing solvent; methylene chloride:methanol=40:1)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution containing 5.1g (0.025 mole) of 2,4-dichlorophenoxyacetaldehyde, 4.25g (0.028 mole) of mandelic acid, and 10.0g (0.07 mole) of boron trifluoide etherate in 250 ml of ether was allowed to stir for 2 hours at ambient temperature, washed with aqueous sodium carbonate and water, dried and concentrated. The residual solid was purified by silica chromatography to give 2.7g of 2-(2,4-dichlorophenoxymethyl)-5-phenyl-1,3-dioxolan-4-one, trans isomer, having a melting point of 68°-71°. washed with aqueous sodium carbonate and water dried concentrated The residual solid was purified by silica chromatography

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a mixture of 44 g of 6,7-dichloro-2,3-dihydro-3-hydroxy-5-methoxy-2-n-propylbenzo[b]thiophene in 275 ml of glacial acetic acid is added 65 ml of boron triluoride etherate and the mixture is warmed on a steam bath until it becomes clear. The solution is stired for 10 mins and then quenched with a mixture of 500 g of ice and 200 ml of a 10% sodium hydroxide solution. The mixture is neutralized with 50% sodium hydroxide solution and then extracted with two 300-ml portions of ethyl ether. The organic layers are combined, washed with 100 ml of a saturated sodium bicarbonate solution, 100 ml of water, dried over anhydrous magnesium sulfate, filtered and the solvent is removed to give an oil. Chromatography of the oil on an alumina column using 9:1-hexane:ethyl ether as eluting solvent gives 31 g of 6,7-dichloro-5-methoxy-2-n-propylbenzo[b]thiophene as an oil. the mixture is warmed on a steam bath until it quenched with a mixture of 500 g of ice and 200 ml of a 10% sodium hydroxide solution extracted with two 300-ml portions of ethyl ether washed with 100 ml of a saturated sodium bicarbonate solution, 100 ml of water dried over anhydrous magnesium sulfate filtered the solvent is removed to give an oil 1-hexane:ethyl ether as eluting solvent

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: As the phosphorous atom of the H-phosphinate intermediate does not present a pair of free electrons and is not a good donor for the introduction of the BH3 group, the boronation procedure requires an in situ intermediate activation of the H-phosphinate with a silylation agent to obtain a disilyl-phosphonite. The H-phosphinates 5 and 10 are activated in situ in anhydrous THF with N,O-bis(trimethylsilyl)acetamide (BSA) for 1 hr. in their corresponding disilyl-phosphonite intermediates. Various boron complexes have been tested in different solvents to optimise the boronation conditions. A rapid and effective boronation was finally obtained with the complex borane-N,N-diisopropylethylamine (BH3:DIPEA). The complexes borane-tetrahydrofuran (BH3:THF), borane-pyridine (BH3:Pyridine), and borane-dimethylsulfide (BH3:Me2S) require significant reduction times and do not improve the yield. In addition, in order to reduce the formation of diboranated products, the quantity of boron complexes was reduced to a maximum of 2 equivalents to obtain the best compromise between consumption of initial material and the appearance of by-products. In situ boronation of the disilyl phosphonites of 5 and 10 with 2 equivalents of BH3:DIPEA results in the formation of -boranophosphonate intermediates. Without isolation, the intermediates obtained were treated with 30% concentrated ammonium hydroxide in methanol (1:1, v/v) to cleave the trimethylsilyl groups thus making it possible to obtain α-boranophosphonates 6a and 6b. The presence of the P—B bond was confirmed by 31P NMR showing a typical peak at 83 ppm and 98 ppm respectively. α-boranophosphonates 6a and 6b are purified by reverse-phase chromatography with a yield of 28% and 32% respectively. to obtain the best compromise between consumption of initial material

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A filtered solution of barium hydroxide octahydrate reacted with an aqueous solution of boric acid to provide hydrated γ barium borate having a barium to boron ratio of 1:2 and having fine particle size. The hydrated γ barium borate was converted to the anhydrous γ form at about 300° to 400° C. Further heating to about 600° to 800° C. converted the product to β-BaB2O4. The conversion to the β-form is preferably during sintering of a ceramic dielectric composition to which the γ-BaB2O4 has been added as a flux.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A sulfurized, boron-containing, heterocyclic compound is prepared by mixing 12 grams of oleylamine, 9.6 grams of styrene oxide and 200 ml of toluene for 30 minutes at room temperature (25° C.) in a single-necked one-liter round-bottomed flask. The flask is placed in a heating mantle and equipped with a water-cooled condenser. The mixture is heated under reflux for three hours producing an oleylamine/styrene oxide adduct. cooled condenser The mixture is heated under reflux for three hours

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To 50.01 g (337.4 mmol) of 1-methoxy-4-(2-propenyl)benzene (Aldrich Chemical Company, Milwaukee, Wis.) dissolved in 300 mL of anhydrous methylene chloride was added dropwise 375 mL (375 mmol) of 1.0 M boron tribromide (Aldrich) in methylene chloride. The reaction was run under nitrogen at room temperature and the mixture was stirred for 1 hour. The mixture was poured over 1000 mL of crushed ice, stirred for 5 minutes, and transferred to a separatory funnel. The organic layer was drained and saved. The boron salts were transferred to a filter containing Celite™ (Aldrich Chemical Co., Milwaukee, Wis.) and the filter containing the salts was washed with portions of methylene chloride and then water. The filtrate was transferred to a separatory funnel and the organic and aqueous layers were separated. The aqueous layer was extracted with four 100mL portions of methylene chloride. The methylene chloride solutions were pooled, dried over anhydrous magnesium sulfate, and filtered. The solvent was removed under vacuum to yield 25.27 g (56%) of crude 4-(2-propenyl)phenol. The crude product was distilled twice at reduced pressure to yield 20.34 g (45%) of 4-(2-propenyl)phenol. The NMR data was consistent with that reported by Rajashekhar and coworkers (J. Biol. Chem. 1984, 259, 6925). was run under nitrogen at room temperature stirred for 5 minutes transferred to a separatory funnel containing Celite™ (Aldrich Chemical Co., Milwaukee, Wis.) the filter containing the salts was washed with portions of methylene chloride The filtrate was transferred to a separatory funnel the organic and aqueous layers were separated The aqueous layer was extracted with four 100mL portions of methylene chloride dried over anhydrous magnesium sulfate filtered The solvent was removed under vacuum

Conditions: temp:20.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of methyl 3-acetyl-1-(2-chlorobenzyl)-2-ethylindole-6-carboxylate (110 mg) in tetrahydrofuran, (5 ml) was added 1M solution of boron in tetrahydrofuran (0.6 ml) in one portion at 0° C. The mixture was stirred at 20° C. for 1 hour, then quenched with water and extracted with ethyl acetate. The organic chase was washed with brine, dried over magnesium sulfate and evaporated in vacuo. The residue was chromatographed or silica gel eluting with a mixture of hexane and ethyl acetate (2:1) to give methyl 1-(2-chlorobenzyl)-2,3-diethylindole-6-carboxylate (42 mg) as colorless crystals. quenched with water extracted with ethyl acetate The organic chase was washed with brine dried over magnesium sulfate evaporated in vacuo The residue was chromatographed silica gel eluting with a mixture of hexane and ethyl acetate (2:1)

Conditions: temp:20.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a solution of methyl 3-acetyl-1-(2-chlorobenzyl)-2-ethylindole-6-carboxylate (110 mg) in tetrahydrofuran, (5 ml) was added 1M solution of boron in tetrahydrofuran (0.6 ml) in one portion at 0° C. The mixture was stirred at 20° C. for 1 hour, then quenched with water and extracted with ethyl acetate. The organic chase was washed with brine, dried over magnesium sulfate and evaporated in vacuo. The residue was chromatographed or silica gel eluting with a mixture of hexane and ethyl acetate (2:1) to give methyl 1-(2-chlorobenzyl)-2,3-diethylindole-6-carboxylate (42 mg) as colorless crystals. quenched with water extracted with ethyl acetate The organic chase was washed with brine dried over magnesium sulfate evaporated in vacuo The residue was chromatographed silica gel eluting with a mixture of hexane and ethyl acetate (2:1)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In still a further embodiment, 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile is prepared according to the present invention. This process includes reacting 1-methyl-pyrrole-2-carbonitrile and a boron agent; coupling the boronated carbonitrile with 6-bromo-4,4-dimethyl-1,4-dihydro-2H-3,1-benzoazin-2-one (the Brofoxine™ reagent) to give 5-(4,4-dimethyl-2-oxo-1,4- dihydro -2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile. See, Scheme 8. Desirably, the boron agent is tri-isopropylborate. The boron agent is typically reacted with the carbonitrile in the presence of lithium di-isopropylamide (LDA) and tri-isopropylborate to give a boronate/borinate mixture which is not isolated. The coupling is typically performed in situ in the presence of a soluble palladium (0) catalyst to give 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile in an unpurified form. In still a further embodiment, 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile is prepared

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: In still a further embodiment, 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile is prepared according to the present invention. This process includes reacting 1-methyl-pyrrole-2-carbonitrile and a boron agent; coupling the boronated carbonitrile with 6-bromo-4,4-dimethyl-1,4-dihydro-2H-3,1-benzoazin-2-one (the Brofoxine™ reagent) to give 5-(4,4-dimethyl-2-oxo-1,4- dihydro -2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile. See, Scheme 8. Desirably, the boron agent is tri-isopropylborate. The boron agent is typically reacted with the carbonitrile in the presence of lithium di-isopropylamide (LDA) and tri-isopropylborate to give a boronate/borinate mixture which is not isolated. The coupling is typically performed in situ in the presence of a soluble palladium (0) catalyst to give 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile in an unpurified form. In still a further embodiment, 5-(4,4-dimethyl-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-1H-pyrrole-2-carbonitrile is prepared